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Caged Protection

Aerogels are mesoporous materials whose very low densities lead to unusual thermal and acoustic properties. However, their high porosity makes them brittle and has limited their use to a few specialized applications. Leventis et al. show that by crosslinking vanadia aerogels with isocyanates to form a conformal coating, they achieve a composite material with an idealized morphology. Unlike more common silica aerogels, mesoporous vanadia consists of entangled wormlike fragments, which fused together at contact points in the polymer-coated composite. In compressive tests, the silica and vanadia aerogels showed similar trends, with the polymer crosslinked materials exhibiting greater strength and toughness. However, one important difference was that the silica aerogels cracked and fractured when highly compressed, whereas the vanadia counterparts could carry a high load even at 91% strain and showed excellent properties under cryogenic conditions. Although vanadia is too expensive to use on a large scale, the authors envision that with the right combination of aerogel morphology and polymer-aerogel interactions, strong aerogels could be prepared from silicon, iron, or aluminum oxides. — MSL